Why are all the textures in my file pink?
Pink means that the texture files are missing.

If the texture files are still on your system, then it sounds like the textures are referenced relative to the blend file (the default behavior). This means that if you move the blend file and you don't move the textures, blender won't be able to find them.

There are several things you can do:


Use the Find Missing Files operator in Info > File > External Data to let blender try to find the files for you:



This will give you a file browser with which you can select a directory which you think contains some (or all) missing files. Blender will then recursively search through all files and subdirectories of the selected directory for files with the same names as the missing files.

Note that if the directory is big (contains lots of files and subdirectories), this might take a while. Blender will appear frozen while the operator runs, but don't panic.
With the blend file in the original location (so the textures are loaded correctly), press Make All Paths Absolute in Info > File > External Data, 
then save the blendfile. Now blender can find the textures (provided they don't move) no matter where the file is on the system.
Pack the textures into the blendfile. Press Info > File > External Data > Pack into blendfile. This will embed the image data into the blendfile itself, so your file may become rather large. However, this means that blender will always be able to find the textures no matter what (even if the file is put on another computer).
Move the textures to be in the same position relative to the new blend as they were to the old blend. E.g., if the textures are in a directory that is in the same directory as the old .blend, move that directory into the directory containing the new .blend.